Charge transport in boron-doped nano MOSFETs: Towards single-dopant electronics

We investigate the hole transport in p-channel field-effect transistors doped with boron, at low temperatures (6-28 K). In transistors with a relatively large dimension, we observe the acceptor-mediated hopping and carrier freezeout, both of which are strongly influenced by the gate bias. In nanoscale transistors, these features turn into single-charge tunneling, i.e., the trapping/detrapping of single holes by/from individual acceptors. The statistics of the appearance of the modulation in a few ten samples indicates that the number of acceptors is small, or even just one, indicating that what we have observed is single-charge-transistor operation by a single-acceptor quantum dot.     

Insertion Reaction of Aldehydes into Zirconacyclopentanes

Aldehydes reacted with zirconacyclopentane derivatives via insertion into the Zr‐sp³C bond to afford the corresponding 7‐membered zirconacycles.     

Visible light-induced photocatalysts with reductive energy storage abilities

Reductive energy from visible light-responsive Au–TiO₂ photocatalyst, which is based on plasmon resonance absorption of Au nanoparticles, can be stored in WO₃ as a reductive energy storage material. About 60% of the charge stored in WO₃ is consumed on the WO₃ and the other 40% is on the Au–TiO₂ by reduction of ambient O₂. Electrochemically pretreated MoO₃ can also be used as an energy storage material.     

Electron paramagnetic resonance of the excited states of the three-spins-1/2 ZnTPP–3-NOPy complex

EPR spectra of the excited quartet and doublet molecular states of (tetraphenylporphinato)zinc(II)covalently bounded to 3-(N-nitronyl-notroxide) pyridine stable radical are modeled in terms of the spin-Hamiltonian given by the sum of the contributions from the radical and triplet moieties, and the interaction between them. The later is represented by anisotropic point dipolar and isotropic exchange electron spin–spin interactions. It is shown that the high field (W-band) EPR spectra depend on energy separation between the electronic doublet (D) and quartet (Q) states. This dependence was utilized to estimate the upper limit of the intensity of exchange interaction between the radical and porphyrin moieties.     

Evaluation of the dynamic range and spatial resolution of nonadiabatic optical near-field lithography through fabrication of Fresnel zone plates

Fresnel zone plates (FZPs) were fabricated in order to evaluate the performance of nonadiabatic photolithography by exploiting the localized nature of optical near fields. This novel photolithography scheme could realize FZPs with structures smaller than the wavelength of the light source used for exposure. The FZP for 325-nm-wavelength UV light could focus the incident light to a spot size of 590 nm. An FZP for focusing soft X-rays was also fabricated and, compared to conventional adiabatic photolithography, showed higher-contrast zones over the whole area of the FZP. This method exhibits a high dynamic range and good spatial resolution, and it was free from artifacts due to the interference of the residual propagating exposure light transmitted through the aperture of the photomask.     

On the Gap between the First Eigenvalues of the Laplacian on Functions and p-Forms

We study the first positive eigenvalue ^(p) ₁(g) of the Laplacian on p-forms for a connected oriented closed Riemannianmanifold (M, g) of dimension m. We show that for 2 p m – 2 a connected oriented closed manifold M admits three metrics g _i (i = 1, 2, 3) such that ^(p) ₁(g ₁)> ⁽⁰⁾ ₁(g ₁),^(p) ₁(g ₂) < ⁽⁰⁾ ₁(g ₂) and^(p) ₁(g ₃)= ⁽⁰⁾ ₁(g ₃).Furthermore, if (M, g) admits a nontrivial parallel p-form,then ^(p) ₁ ⁽⁰⁾ ₁ always holds.     

161Dy Mössbauer spectra for cyano coordination polymer compounds

Four kinds of Dy(III) hexacyanometalates (II or III), DyFe(CN)₆·4H₂O (1), KDyFe(CN)₆·4H₂O (2), DyCo(CN)₆·4H₂O (3), and KDyRu(CN)₆·4H₂O (4) have been investigated by ¹⁶¹Dy Mössbauer spectroscopy. ¹⁶¹Dy isomer shifts of four compounds fall in the range of +3 ionic compounds. Although all spectra 1-4 show an almost symmetric line, the broadening of the line-width is observed on lowering the temperature due to the paramagnetic relaxation. As a parameter of intermolecular force constant, the M² value obtained for ¹⁶¹Dy of 1 is slightly larger than that of 2.     

Reaction of Titanium Isopropoxide with Alkanolamines and Association of the Resultant Ti Species

A clear alcoholic solution of titanium alkoxide with an addition of various alkanolamines is suitable for a sol-gel coating of titania films. The reaction of titanium isopropoxide, Ti(OPr ⁱ )₄ (TIP), with alkanolamines, such as triethanolamine (TEAH₃), diethanolamine (DEAH₂), and N-ethyldiethanolamine (EDEAH₂), and an association of the Ti species in the resultant mixtures were examined via liquid-state nuclear magnetic resonance (NMR), infrared spectroscopy (IR), and cryoscopy measurements. Regardless of the kinds of the alkanolamines used, the IR and NMR spectra showed that alcohol exchange reactions occurred between the alcoholic moieties in alkanolamines and the isopropoxy groups in TIP, and that the N atom in the alkanolamines might be datively bonded to Ti. In the DEAH₂ and EDEAH₂ systems with the molar ratio of amine/TIP = 1, the results of the NMR and cryoscopy measurements showed that an association degree of the formed Ti species increased with an increase in the concentration of TIP, according to the thermodynamical equilibriums of associations between various oligomers. The increase was larger in the DEAH₂ system than in the EDEAH₂ one, because of the larger equilibrium constants due to the smaller size of the DEA group. In the system of EDEAH₂/TIP = 2, the NMR spectra showed that only one kind of oligomer was formed as a Ti species, independent of the concentration of TIP. The oligomer may be a much more stable species than other species. The cryoscopy results showed that the oligomer had a tetrameric structure.